[PATCH v9 05/10] efi_loader: check lowest supported version

[Masahisa Kojima]

The FMP Payload Header which EDK II capsule generation scripts
insert has a firmware version.
This commit reads the lowest supported version stored in the
device tree, then check if the firmware version in FMP payload header
of the ongoing capsule is equal or greater than the
lowest supported version. If the firmware version is lower than
lowest supported version, capsule update will not be performed.

Signed-off-by: Masahisa Kojima <masahisa.kojima at linaro.org>
---
No update since v7

Changes in v7:
- return immediately if efi_firmware_capsule_authenticate() fails

Changes in v6:
- get aligned to the latest implementation

Changes in v5:
- newly implement the device tree based versioning

Changes in v4:
- use log_err() instead of printf()

Changes in v2:
- add error message when the firmware version is lower than
  lowest supported version

 lib/efi_loader/efi_firmware.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/lib/efi_loader/efi_firmware.c b/lib/efi_loader/efi_firmware.c
index ae631f49f7..b557738370 100644
--- a/lib/efi_loader/efi_firmware.c
+++ b/lib/efi_loader/efi_firmware.c
@@ -419,7 +419,8 @@ static void efi_firmware_get_fw_version(const void **p_image,
  * @image_index:	Image index
  * @state:		Pointer to fmp state
  *
- * Verify the capsule file
+ * Verify the capsule authentication and check if the fw_version
+ * is equal or greater than the lowest supported version.
  *
  * Return:		status code
  */
@@ -429,11 +430,27 @@ efi_status_t efi_firmware_verify_image(const void **p_image,
 				       u8 image_index,
 				       struct fmp_state *state)
 {
+	u32 lsv;
 	efi_status_t ret;
+	efi_guid_t *image_type_id;
 
 	ret = efi_firmware_capsule_authenticate(p_image, p_image_size);
+	if (ret != EFI_SUCCESS)
+		return ret;
+
 	efi_firmware_get_fw_version(p_image, p_image_size, state);
 
+	image_type_id = efi_firmware_get_image_type_id(image_index);
+	if (!image_type_id)
+		return EFI_INVALID_PARAMETER;
+
+	efi_firmware_get_lsv_from_dtb(image_index, image_type_id, &lsv);
+	if (state->fw_version < lsv) {
+		log_err("Firmware version %u too low. Expecting >= %u. Aborting update\n",
+			state->fw_version, lsv);
+		return EFI_INVALID_PARAMETER;
+	}
+
 	return ret;
 }
 
-- 
2.34.1